Hansen et al.: RIP

[Update: Or, maybe not.]

Via twitter comes news of the sad demise of "Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2 °C global warming is highly dangerous"; Review status: This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). A final paper in ACP is not foreseen. My view at the end of August was that Peter Thorne's review was "substantially negative about the paper"; it looks like the editor has gone with that and similar views. In essence, its a sad train-wreck; only read on if you like such. I feel somewhat cruel in even blogging it. But Hansen is a big boy, and he chose to put this up in public.

First, timing. I've now re-read Eli Follows Up written on the 12th of October (a successor to the critically acclaimed Eli follows through) which tells me that "The editor, Frank Dentener, has closed the open discussion and thrown the paper into the second stage of review... The authors are now expected to publish responses to the comments and reviews". Which explains the flurry of replies by H on the 13th. In consideration of the review by Drijfhout et al., "Eli judge[d] that the editor will pay serious attention to these arguments and Hansen, et al, will have to meet their challenges".

But before we get to that, let's look at a comment by Greg Flato, another serious player. Its not new, but had slipped my attention in the mass of other comments. Its probably the most critical of all - ignoring the nutters, of course.

given the way the paper is organized, it is difficult for a reader to connect assumptions made in the model forcing (sections 3.2 and 4.3) to their justification based on paleo-climate reconstructions (section 2.1) and modern observations (section 7.3). What is important is that the prescribed freshwater forcing scenarios have an exponentially increasing form with doubling times of 5, 10 and 20 years. The most extreme of these has sea level rising 5m by the year 2060. This assumes freshwater flux could rapidly reach values up to 8Sv. To put this in perspective, it is about 1800 times the currently observed melt rate for west Antarctica... Prolonged exponentially increasing ice-sheet loss is clearly unphysical and so the authors arbitrarily terminate freshwater input once the associated sea-level rise reaches 5m – it is zero thereafter... The authors provide no assessment of the likelihood of any of their scenarios, and do not cite most of the previous studies that have explored the response of the climate system to much less dramatic freshwater input... They also do not justify the manner in which this freshwater is introduced into the ocean (as liquid water with a temperature of -15◦C, pg. 20079)... simulated global temperature drops to roughly 1.4◦C below preindustrial levels... This is in striking contrast to essentially all published projections of 21st century climate change, and so places a very large burden on the authors to provide evidence in support of rapid global cooling in the face of rising greenhouse gas concentrations...

Adding the melt to the ocean as water at -15 oC is a "WTF?" moment. Also Flato points out, somewhat more diplomatically, what I said before: hosing is passe, its been done to death. So how do H et al. respond? In a rather long rambly sort of way that ends up with "In all of these model runs we used -15°C as the temperature of the freshwater added to the ocean mixed layer. If a large fraction of the ice sheet discharge is icebergs, the cooling effect would be larger than in our experiments". So I think the point is that the latent-heat equivalent of dropping the ice in the ocean and having it melt, would be inserting the ice as water at -15 oC. Except, it wouldn't be: -15 is just a nice round number, as H implies in the reply, actually it should be a different number. Um. And none of this info is in the original paper? I think we're back at my suggestion: the paper is too long, and clearly needs to be broken up into sub-papers that are manageable.

And... H et al. just won't learn: having been criticised pretty strongly for mixing science and advocacy, the end of the response to Flato is Let us hope that we are smart enough not to perform an empirical test using the real world with a forcing of the business-as-usual magnitude. Really? Does say to him "please, just don't say that, this isn't the place"? I'm speaking as a famously diplomatic person, you understand.

But the make-or-break one is Drijfhout et al.: are six people enough to stand up to Hansen? Well, yes. They start off fairly gently with The analysis does not contain any process that is physically impossible (albeit sometimes unlikely)), nor present principally flawed interpretations of the paleo data (albeit often biased to the upper end of uncertainty measures) but fairly soon get to

The title of the paper is more suggestive than is justified by the scientific evidence. The conclusions
cannot be regarded as being robust, as they are insufficiently supported by both modeling results
and observations

which is fatal. H et al.'s response is very short, and is the reply of someone who has given up. The most obvious example of this is

Extreme events are much more likely to occur after 2100 – therefore we recommend to avoid terminology such as “dangerous”. Hmm, yes, I guess that we should not be concerned about anything that happens 85 years from now – the dickens with those characters. The Dutch can migrate to Switzerland, after all.

If you're going to write that kind of thing, stick to blogs and op-eds.


* "Unfortunately, while computers continually surprise us with what they can be used for, almost nothing is known about what they cannot do." - via QS
* Science Isn’t Broken: It’s just a hell of a lot harder than we give it credit for. Includes nice p-hacking toy.

More like this

Whether the ice bergs are -20 or -10°C, that hardly makes a difference, the melting energy and the uncertainty in the amount of fresh "water" count.

What killed the manuscript were the answers of Hansen. Never seen anything like it. Replies to reviews are normally polite, specific and technical.

The scientific literature is not the right place for activism.

By Victor Venema … (not verified) on 17 Oct 2015 #permalink

Something funny is going on with the whole bunch of 13.10 replies that were dumped on APCD. What is not clear but a bit of time should tell. Hansen can be annoyed, but he is always smooth, and many of the posted replies were, to put it simply in the wrong place and duplicated.



[Are you suggesting that come of the comments weren't finished? Just emails? It an intriguing idea, but I'm doubtful -W]

By Eli Rabett (not verified) on 17 Oct 2015 #permalink

I tried to get through the draft paper but it was just too long and took too much of an 'everything including the kitchen sink' for me to follow. Even the storm wave hypothesis for something not too far outside of my ballpark, the large stratigraphically-displaced limestone blocks, left me deeply skeptical.

And I missed the reference to -15°C water, which even if the authors were justified in using on energy grounds should have been spelled out as a mixture of water + 20% ice at 0°C

And it was impossible not to notice words like dangerous, urgent, threatening, ungovernable, etc. and conclude that their inclusion in a technical paper weakened it badly. Conclusions and actions should follow from objective and defendable technical findings, not lead them, as this paper gave the (possible) impression of doing.

It will be interesting to see what the reaction of the climate-change deniers will be, with their repeated claims of alarmism, exaggeration and "pal review" in climate science. Will they admit that peer-review works, or will they just attack the character and competence of Hansen and his co-authors? My money's on the latter.

[My guess is that they will spin is as something like "science rejects Hansen"; but you're right, this does provide a counter-example to the meme that "alarmist can publish anything" or whatever their pet meme is -W]

Timothy Gowers is simply wrong about computers. Some predicates are proveably undecidable, some are proveably uncomputable and some are proveably intractable. Much experience suggests that apparently intractable predicates are indeed intractable.

[I don't think that was the kind of thing he was thinking about; and the things that are provably undecidable apply to people just as well. Consciousness, that kind of stuff -W]

By David B. Benson (not verified) on 17 Oct 2015 #permalink

Interesting to remember the ACP comments on the paper "Where do winds come from?" by Makarieva et al:
"Normally, the negative reviewer comments would not lead to final acceptance and publication of a manuscript in ACP. After extensive deliberation however, the editor concluded that the revised manuscript still should be published – despite the strong criticism from the esteemed reviewers – to promote continuation of the scientific dialogue on the controversial theory."

Apparently Hansen wasn't controversial enough.

[I didn't pay attention to the Makarieva drivel at the time. Which probably turns out to be correct. But that, however stupid, had the virtue of novelty (I would still have argued against publication, has I been asked). H et al. isn't novel in approach; just pushing the boundaries further -W]

By Nick Stokes (not verified) on 17 Oct 2015 #permalink

No, Eli is wondering where this (as Victor rightly says) crap came from. It is completely out of character for Hansen, but believable as a set of notes he was using to structure replies.

If you look at all of the 13.10 AU replies there is a lot of repetition and more (plus which these replies were not posted on 15.10 @ 5 pm.

Read Rabett Run

By Eli Rabett (not verified) on 17 Oct 2015 #permalink

Those are indeed weird responses from Hansen.

I sometimes tell my PhD students to write (on paper) their brutally honest rant about some reviewer comments they may have received, just to get rid of their frustrations. "The Dutch can migrate to Switzerland, after all." sounds like a comment they may produce in such a rant.

I wonder what Hansen's co-authors think about this.

Too bad.

I was actually hoping for publication, in a sort of E&E way, the potential 'damage' done to the ACP brand name, but further, the very long term end-of-career 'damage' to Hansen and Hearty.

The replies on 13 OCT 2015 did not include replies to either Archer or Thorne. I found that rather odd (specifically with respect to Thorne).

Hansen15 really needed a least one other AOGCM to compare modelling results. Hansen has made statements to the affect of (1) the process based ice sheet models are too slow and (2) almost all, if not all, AOGCM's over mix the oceans. Running a rather course resolution model also doesn't help.

IMHO the aggressive hosing, and perhaps (idle aspersion casting speculation on my part), an underspecification of the ocean mixing parameterization could have produced the results seen in Hansen15.

Finally, absent a deep water tsunami modeler and absent a farfield water waves (NOAA's Wavewatch III) modeler and absent a nearshore wave transformation forcing and runup processes modeler, that superstorm conjecture is DOA.

You have a superstorm conjecture, it is hydrodynamically testable with current modelling technologies (mostly numerical and possibly physical for runup and forcings (at say OSU's tsunami facility)), then test it!

By Everett F Sargent (not verified) on 18 Oct 2015 #permalink


You really need to read Hansen's reply dated 21 September 2015 (which is, you know,after the open review deadline) ...
(HTML version)

(same as above but PDF version)

and Hansen's PDF version of the discussion paper (inline figures saves time in running up/down the ACP version) ...

Careful reading of the original paper talks about 10, 20 and 40 year doublings throughout. The paper actually suddenly used 5, 10 and 20 year doublings. It sort of just jumps out of nowhere so to speak with no real explanation given considering the rest of the original 10, 20 and 40 year doubling text. So the 40 year doubling was dropped and the 5 year doubling was added (if one is just going to add the 5 year doubling (e. g. per Hansen's online update to H&S(2011)) one should also include the 40 year doubling IMHO. The real reason Hansen15 didn't do a 40 year doubling is that a 20 year doubling only get's to ~0.75 meters above current sea level by 2100.

From the 21 SEP 15 HTML ...

"In our paper1 we discuss potential ice melt doubling times of 10, 20 and 40 years, which respectively would lead to multi-meter sea level rise in about 50, 100, and 200 years. For the sake of analyzing the effect of freshwater on ocean circulation and planetary energy balance, we made climate simulations for doubling times of 5, 10 and 20 years, omitting 40-year doubling because of its larger computing requirement. These cases were sufficient for conclusions about the effect of freshwater on the planetary energy balance and shutdown of overturning ocean circulations (AMOC and SMOC)."

So the 'excuse' for not including the 40 year doubling is "its larger computing requirement." Somehow I seriously doubt that excuse.

See also Figure 7 (which is the 1st derivitive of the -12 years of SMB data ...

"Fig. 7. Greenland and Antarctic ice mass change based on Velicogna et al. (2014)[9] gravity data. Green (dashed) curve for Greenland is freshwater discharge used in our climate model. Blue curves are gravity data for Greenland (and Antarctica) only; small Arctic ice caps and ice shelf melt are additional. Monthly data points are the difference between the ice sheet mass at the point plotted and the mass in the same month one year earlier. The 12-month running mean is plotted at the mid-point of the year."

The straight line for the rate would be a quadratic fit once integrated. There's no way possible for one to objectively judge which is a better fit (for 10 year doubling quadratic or exponential). As to the 5 year doubling, that one would start to emerge from the CU GMSL data set in only 5-10 years (2 mm/yr at 5 years and 4 mm/yr at ten years) from now (plot the SMB data versus the GMSL data then compare the RMS (or S/N ratio) from both datasets). Sans the current ENSO bump.

Again from the 21 SEP 15 ...

"Furthermore, we argue that our model and many ocean models understate the stratification effect because of excessive small scale ocean mixing."

References, fact or belief.

"Given all the evidence, a claim that a scenario with 600-900 ppm CO2 forcing within a century would not yield multi-meter sea level rise this century is an extraordinary claim that would require extraordinary proof. Today’s ice sheet models are not capable of providing that proof."

Well CO2 from MLO is still somewhere between 2-2.5 mm/yr so getting to 6-9 mm/yr (mean rate per century) is going to take some very big BAU emissions to get to an average of 6-9 mm/yr on a century timescale. So the 'extraordinary proof.' would appear to be Hansen proving that by 2100 we'll be at an average of 6-9 mm/yr for the 21st century.

By Everett F Sargent (not verified) on 18 Oct 2015 #permalink


Last paragraph mm/yr should be ppm/yr for CO2 rate.

Sorry about that.

By Everett F Sargent (not verified) on 18 Oct 2015 #permalink

Being wrong in uncharted territories of scientific progress does not damage one's career, Everett. It's a feature, not a bug.

By Thomas Lee Elfiritz (not verified) on 18 Oct 2015 #permalink

I think the paper has some very interesting things in it. The part where he shows snowfall declining on the continent - Antarctica... in the recent Freeman Dyson interview he suggested there could be ways to increase snowfall on Antarctica.

[Yeah, but don't forget that FD is a nutter -W]

It is not Easter - I did just check - for the paper is resurrected. I'm thinking an unsupervised script rather than anything more conspiratiorial by the way.

By Peter Thorne (not verified) on 19 Oct 2015 #permalink

Speaking of trains overshooting the end of the rails (your illustration), there's a better picture somewhere of a BART train hanging off the end of the elevated tracks with its nose down in the parking lot of the Fremont CA station.

This event, tho' not this picture:

"... the IEEE attempted to assist the three engineers by filing an amicus curiae (friend of the court) brief in their support. The IEEE asserted that each of the engineers had a professional duty to keep the safety of the public paramount and that their actions were therefore justified. Based on the IEEE code of ethics, the brief stated that engineers must “notify the proper authority of any observed conditions which endanger public safety and health.” The brief interpreted this statement to mean that in the case of public employment, the proper authority is the public itself [Anderson, 1980]. This was perhaps the first time that a national engineering professional society had intervened in a legal proceeding on behalf of engineers who had apparently been fulfilling their duties according to a professional code of ethics.

"Safety concerns continued to mount as BART was put into operation. For example, on October 2, 1972, less than a month after BART was put into revenue service, a BART train overshot the station at Fremont, California and crashed into a sand embankment...."

The IEEE's position on the matter of responsibility is perhaps worth commemorating by the AGU members who ride the BART trains every year in December.

Of course, there are others:

By Hank Roberts (not verified) on 26 Oct 2015 #permalink

Little early to say, but SLR may be accelerating nicely.

From less than 2.0 mm/year in late 19th century, to 2.3 mm/year in early 20th century, to ~ 2.7 mm/year around 1993.

Last year we saw over 3 mm/year, then 4.1 mm/ year. The first nine months of 2015 alone saw 10 mm, although a similar spike was seen in 1997-1998.

In the next few years we should get a better fix on the rate of change, but it sure seems to be ramping up quickly.

By Gingerbaker (not verified) on 27 Oct 2015 #permalink

A "thorough debunking" is different. Not having sufficient quality for the scientific literature does not automatically mean that a manuscript is of WUWT quality.

By Victor Venema … (not verified) on 03 Nov 2015 #permalink

In reply to by Paul Matthews (not verified)